package My::Class;
use Moo;
use MooX::StrictConstructor;
has 'size' => ( is => 'rw');
# then somewhere else, when constructing a new instance
# of My::Class ...
# this blows up because color is not a known attribute
My::Class->new( size => 5, color => 'blue' );

Simply loading this module makes your constructors "strict". If your constructor is called with an attribute init argument that your class does not declare, then it dies. This is a great way to catch small typos.

A class that uses MooX::StrictConstructor but extends another class that does not will not be handled properly. This code hooks into the constructor as it is being strung up (literally) and that happens in the parent class, not the one using strict.

A class that inherits from a Moose based class will discover that the Moose class's attributes are disallowed. Given sufficient Moose meta knowledge it might be possible to work around this. I'd appreciate pull requests and or an outline of a solution.

MooseX::StrictConstructor documents a trick for subverting strictness using BUILD. This does not work here because strictness is enforced in the early stage of object construction but the BUILD subs are run after the objects has been built.